THE AUSTRALIAN NATURALIST. 197 
the caterpillar once more in her mandibles, backs down the 
burrow, dragging with her the lifeless body of the cater- 
pular. After about ten seconds she reappeared, and pro- 
ceeded at once to block up the tunnel entrance. At first 
with the aid of the legs, she throws down+a quantity of 
fine earth, ramming it down at intervals with the head by 
short, sharp rushes. She then collects the larger pellets 
of earth previously taken from the tunnel, and with the 
aid of her mandibles, carefully places them in position on 
top of the finer earth, so as to make a close, well-packed 
filling. larger pellets again are then used to fill up the 
burrow to the original level, and the top is then covered 
by a leaf, on top of which is placed a few scattered 
péllets in order to make it as nearly as indistinguishable 
as possible. So the nest is completed, and the young wasp 
larvae left to develop underground, the parent wasp ap- 
parently taking no further interest in the nest. Some 
three or four days later I dug up several of the wasp 
burrows, and in every case a single caterpillar only was 
found in the cell at the extremity of each burrow. To 
each caterpillar was attached a small wasp larvae, the 
head only of which was inserted through the epidermis of 
the caterpillar, which was apparently dead, except for a 
slight twitching movement of the posterior extremity of 
the body. 
Another very.common wasp in the vicinity of the 
Experiment Station. was the common ““NIud Dauber,’’ 
Pelopacus laetus, a solitary wasp, which has the some- 
what curious habit of choosing the interior of human habi- 
tations as the spot most suitable for the formation of 
its nests. The nest is constructed of soft mud, and is 
built in any part of the room which suits the fancy of 
the insect. In the laboratory at the Experiment Station 
two or three of these insects were always present, ap- 
parently with the object of choosing a suitable site to 
build their nest. One of them, after careful searching, 
chose a spot in the darkest corner of the laboratory, and 
constructed her nest on the top of a tin on a narrow shelf 
about five feet from the ground. From the time the door 
of the laboratory was opened in the morning until closed 
at night, the wasp never ceased in its work of building 
